The invention provides a method of forming a magnetic layer with stable magnetic properties and stable recording-and-reproducing properties, by uniformizing the distribution of oxygen radical concentration upon reactive sputtering, and thereby uniformizing the concentration of oxygen to be taken into the magnetic layer along the plane direction. That is, the invention relates to a method of forming a magnetic layer by reactive sputtering, which comprises: placing a substrate in a reaction container; arranging a pair of electrode units comprising sputtering electrodes and targets which are disposed on surfaces of the sputtering electrodes and which contain chromium other than the oxide thereof, so that the electrode units respectively face both sides of the substrate while the targets are on the substrate sides; feeding an argon-water mixture gas to vicinities of the respective surfaces on the substrate sides of the pair of electrode units; and applying reactive sputtering so that the chromium other than the oxide thereof contained in the targets can be made into chromium oxide as a constituent to form the magnetic layer having the granular structure.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method of forming a magnetic layer for use in a magnetic recording medium in which a magnetic layer having a granular structure containing at least cobalt and chromium is formed on both sides of a substrate by reactive sputtering, which comprises: placing said substrate in a reaction container; arranging a pair of electrode units comprising sputtering electrodes and targets which are disposed on surfaces of the sputtering electrodes and which contain chromium other than the oxide thereof and cobalt oxide, so that the electrode units respectively face both sides of said substrate while said targets are on the substrate sides; feeding an argon-water mixture gas to vicinities of the respective surfaces on the substrate sides of said pair of electrode units; applying reactive sputtering so that the chromium other than the oxide thereof contained in said targets can be made into chromium oxide as a constituent to form the magnetic layer having the granular structure; and applying reactive sputtering so that the cobalt oxide contained in said targets can be made into cobalt as a constituent to form magnetic grains in the magnetic layer having the granular structure.
2. The method of forming a magnetic layer according to claim 1 , wherein the magnetic layer is formed by reactive sputtering while feeding the argon-water mixture gas to the vicinities of the respective surfaces on the substrate sides of said pair of electrode units so that the gas can flow from the peripheral parts toward the central parts, as well as discharging a post-reaction waste gas from the longitudinally opposite ends of said reaction container.
3. The method of forming a magnetic layer according to claim 1 , wherein said magnetic layer is a perpendicular magnetic layer whose magnetic anisotropy is perpendicular to the surface of the substrate.
4. The method of forming a magnetic layer according to claim 1 , wherein said magnetic layer contains, in addition to the chromium oxide, one or more types of oxide(s) selected from the group consisting of Si oxide, Ti oxide, W oxide, Co oxide, Ta oxide, and Ru oxide, as a grain boundary constituent for forming the granular structure.
5. The method of forming a magnetic layer according to claim 1 , wherein the thickness of said magnetic layer is within a range of 1 nm to 15 nm.
6. The method of forming a magnetic layer according to claim 1 , wherein said magnetic layer contains oxide(s) within a range of 3 mole % to 15 mole %.
7. The method of forming a magnetic layer according to claim 1 , wherein said substrate is a disk-shaped substrate for use in a magnetic recording medium, and said magnetic layer having the granular structure is a magnetic recording layer in the magnetic recording medium.
8. The method of forming a magnetic layer according to claim 1 , which comprises: arranging on the substrate sides of said pair of electrode units, a gas inlet pipe whose inner peripheral wall is provided with a plurality of gas outlet apertures annularly along the circumference; and introducing said mixture gas into said gas inlet pipe and discharging the gas from the respective gas outlet apertures to thereby feed said mixture gas to the vicinities of the respective surfaces on the substrate sides of said pair of electrode units, so that the gas flows from the peripheral parts toward the central parts.
9. The method of forming a magnetic layer according to claim 2 , wherein an exhauster device for discharging said waste gas comprises a turbo-molecular pump.
10. The method of forming a magnetic layer according to claim 2 , wherein an exhauster device for discharging said waste gas comprises a cryopump.
11. The method of forming a magnetic layer according to claim 2 , wherein the method employs an apparatus which comprises a first exhauster for discharging said waste gas from one longitudinal end of said reaction container and a second exhauster for discharging the gas from the other end, and at least either one of these exhausters has two vacuum pumps.
12. The method of forming a magnetic layer according to claim 1 , wherein a plurality of pairs of said electrode units are used, and magnetic layers are formed in parallel on both sides of a plurality of substrates.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
November 9, 2009
October 4, 2011
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